This invention relates generally as indicated to a method of making a roof flashing in which the entire flashing including both the collar and base member are made of elastomeric material.
It is well-known to make the collar portion of a roof flashing out of a suitable elastomeric (plastic) material which forms an effective weather-proof seal around an upstanding pipe and the like protruding through the sloping roof of a building. However, heretofore it was the usual practice to make the base member out of metal, and provide a mechanical joint between the base member and collar. One such roof flashing which has been very well received and widely used and accepted throughout the industry is shown in applicant's own U.S. Pat. No. 3,313,559 assigned to the same assignee as the present application. However, the use of such a metal base adds considerably to the cost and weight of such a roof flashing. Also, such a metal base is more bulky to ship and store, and is susceptible to damage by bending or denting same.
To eliminate these objections, considerable efforts have been put into making the base member as well as the collar out of plastic, with varying degrees of success. There are, for example, some all-plastic roof flashings in which both the collar and base member are integrally molded as a single unit. However, this is an expensive molding operation, and places some restrictions on the type of seal that can be formed between the collar and pipe. Also, this requires that the base member be made out of the same elastomeric material as the collar, which may unnecessarily add to the cost of the flashing, in that the material specifications for the collar are much more demanding than those for the base member, because of the requirements of the collar to be sufficiently flexible and pliable in order to form the desired fluid-tight seal with a range of pipe sizes on different pitched roofs.
Efforts have also been made to make the collar and base member separately so that different types of elastomeric materials could be used for each member. However, this creates additional problems in how to provide a secure and effective joint or connection between the collar and base member. Mechanical connections of one type or another have been tried, but they have generally not been very successful in that they are susceptible to being pulled apart, and also add considerably to the overall cost of manufacture and assembly of the flashing.